Beverage cans are in such general use that their dimensions and opening features have become standardized. Some other containers have adopted the same end configuration. Once open, the containers are at the mercy of accidental spillage, and deterioration of the degree of carbonation. For women, tipping up an open can, and swilling out its contents, is a somewhat indelicate operation; and for children, it invites disaster to the clothing. Several attempts have been made to produce snap-on covers for a standard beverage can that would close off the can when the contents were not wanted at that moment, and provide the effect of a drinking straw when the contents were desired. Low cost and simplicity of construction are critical factors. The fact that these devices have not been in wide use is some evidence of their shortcomings.